As the commercial marking of goods to an increasing extent is made by using the so-called bar code which can be read electronically and thus facilitates the registration of the purchased goods in the cash register, the common price tag on the goods will be superfluous from a commercial point of view and thus can be dispensed with if this is permitted by the authorities concerned. Then, the marking on the edges of the shelves will be much more important, and for such marking there are used today practically without exception signs which comprise a holder with manually interchangeable figures or other characters. Price changes in the goods assortment, which may occur every day to a great extent as far as everyday commodities are concerned, include an extensive manual work for the shop staff in changing the several signs which, moreover, are disadvantageous, because it is not difficult for a person to change unauthorizedly the information on a sign, if he wishes to do so.
However, according to the periodical Supermarket No. 7-8/84, page 25, an electronic marking for the edges of shelves has been proposed recently, which eliminates the drawbacks of the "manual" shelf edge marking. In that case a display having illuminated digital figures, is provided on the edge of the shelf and can be controlled from the shop computer such that a changed price will be shown immediately and without further manual steps by the display indicating the price of the article for which the price has been changed. The electronic shelf edge marking also permits that there is initiated in a shop a price test or selectively applied price activities during specific selected business hours. However, the electronic shelf edge marking proposed according to said periodical would require for the operation thereof an extensive wiring not least for the power supply of the displays.